1. Field of the Invention
The present invention relates to a wet type image forming apparatus that uses ink and the like, and an information processing system using the wet type image forming apparatus. More particularly, the present invention relates to a technique for detecting a liquid surface level of an ink tank in a manner of many steps.
2. Description of the Related Art
A wet type image forming apparatus which uses a liquid developer, ink and the like is used in a printer, a copier and the like. Conventionally, as a method for checking a remaining amount of an ink tank of the wet type image forming apparatus, there are a method based on a visual inspection by a user, and another method for automatically detecting a liquid surface level of an ink tank and then reporting it to a user. A wet type image forming apparatus is known in which a capacitance sensor and a light sensor using a light emitting device and a light sensing device are used, in order to detect a liquid surface level of an ink tank. However, those sensors are typically expensive, which causes a cost of the wet type image forming apparatus to be increased.
Japanese Laid Open Utility Model (JU-A-Heisei, 1-85853) discloses a liquid developing device for detecting a liquid surface level of an ink tank by using a reed switch, in order to make a price cheaper. This liquid developing device has an excess toner recovery device for recovering an excessive toner on a dielectric-coated paper after developing with an electrostatic recording head by using a liquid toner from a liquid toner tank. Two reed switches are mounted in this excess toner recovery device. Among them, one reed switch is mounted in a vicinity of an upper end, and the other reed switch is mounted in a vicinity of a bottom tip. ON/OFF operations of the two reed switches are controlled on the basis of a position of a float magnet which is moved upwardly or downwardly within the excess toner recovery device, in accordance with an excess liquid amount. The reed switch mounted in the vicinity of the upper end is turned ON if the excess liquid amount within the excess toner recovery device is likely to overflow. Accordingly, an occurrence of clogging in a toner exhaust pipe of the excess toner recovery device is detected. Also, such a fact that there is no liquid toner in the liquid toner tank is detected when the reed switch mounted in the vicinity of the bottom tip is turned ON.
In a recent environment in which a plurality of users use a network printer through a remote control and thereby use a large amount of ink, the ink that is consumptive material is hugely exhausted. Thus, it is necessary to report a remaining amount of ink to the user in a careful manner (in a manner of many steps) and also necessary to attain a cheap price.
However, in the liquid developing device disclosed in Japanese Laid Open Utility Model (JU-A-Heisei, 1-85853), the cheap price is attained by using the reed switch. However, the detection of the excess liquid amount is done only in the two steps of the vicinity of the upper end and the vicinity of the bottom tip. Thus, this does not satisfy the request of the report of the remaining amount in the careful manner (in the manner of many steps).
Also, because the two reed switches are used in order to detect the excess liquid amount in the manner of two steps, it is not efficient. Moreover, the liquid amount within the liquid toner tank is only estimated based on the excess liquid amount within the excess toner recovery device detected by the two reed switches. Thus, it does not directly detect the liquid amount in the liquid toner tank itself.
As a related technique, Japanese Laid Open Patent Application (JP-A-Showa, 62-263059) discloses a liquid jet recording apparatus. This liquid jet recording apparatus is equipped with a float having a magnet inside of a tank, and a Hall element responding to the magnet at a position where a recording operation is not obstructed, outside the tank. Thus, the remaining liquid amounts in a plurality of liquid tanks can be detected with only one Hall element.
Japanese Laid Open Patent Application (JP-A-Showa, 63-147650) discloses a recording apparatus. This recording apparatus has a plurality of pairs of light paths arranged in a vertical direction at a wall of an ink tank. The light paths in combination with a floating body that can shut off those light paths can detect whether an ink amount within the ink tank is large or small, on the basis of a position of the floating body. A recordable amount is reported to an operator, in accordance with the detected result.
Moreover, Japanese Laid Open Patent Application (JP-A-Heisei, 8-25646) discloses a recording apparatus and an information processing system. The recording apparatus includes an ink amount sensor, a float member and a supporter. The ink amount sensor is composed of a light emitting device and a light sensing device for receiving a light from the light emitting device. The float member is composed of at least two sections whose widths are different from each other. The support member floats the float member along a predetermined direction at a predetermined position within an ink cartridge, in which at least a part of the float member is inserted so as to slide. Then, it detects a remaining ink amount within the ink cartridge in a manner of many steps.
Therefore, an object of the present invention is to provide a wet type image forming apparatus which can detect a remaining amount of an ink tank in a manner of many steps by effectively using a reed switch as a liquid surface level detecting device, and provide an information processing system using the wet type image forming apparatus.
In order to accomplish the object, a wet type image forming apparatus according to a fist aspect of the present invention comprises an ink tank, a float, n reed switches and a detector.
The ink tank stores ink therein. The float has a magnet, and moves upwardly or downwardly in association with a change of a liquid surface of the ink stored in the ink tank. The n reed switches are distributedly arranged from an upper portion of the ink tank to a lower portion thereof and are turned ON or OFF in response to the magnet, where n is an integer equal to or more than 2. The detector detects an amount of the ink in the ink tank in m steps based on a combination of ON and OFF states of the n reed switches, where m greater than n, m is an integer.
This wet type image forming apparatus may further comprise a columnar body which is fixed in the ink tank, wherein the n reed switches are arranged on the columnar body. In this case, the m may be equal to 2xc3x97n.
In this wet type image forming apparatus, the detector may include a detecting circuit, a memory and a remaining amount judging portion. The detecting circuit detects an ON or OFF state of each of the n reed switches. The memory stores therein a correspondence relation of the combination of the ON and OFF states of the n reed switches and the amount of the ink in the ink tank, wherein the amount is represented in 2xc3x97n steps. The remaining amount judging portion judges the amount of ink in the ink tank based on the correspondence relation stored in the memory and the combination of ON and OFF states of the n reed switches detected at the detecting circuit.
In the wet type image forming apparatus, the n reed switches may be arranged on the columnar body to define response ranges in which each of the n reed switches is turned ON independently, response ranges in which two of the n reed switches adjacent to each other are turned ON and a non-response range formed at any one of an upper end portion and a bottom tip portion of the columnar body in which all of the n reed switches are turned OFF.
Also, in the wet type image forming apparatus, the 2xc3x97n steps may be classified into n steps in which only one of the n reed switches is turned ON, nxe2x88x921 steps in which every two of the n reed switches adjacent to each other are turned ON and one step in which all of the n reed switches are turned OFF.
Also, the wet type image forming apparatus may further comprise a display which displays the ink amount judged by the remaining amount judging portion.
Furthermore, in this wet type image forming apparatus, the m may be equal to 2xc3x97n+1. In this case, the 2xc3x97n+1 steps may be classified into n steps in which only one of the n reed switches is turned ON, nxe2x88x921 steps in which every two of the n reed switches adjacent to each other are turned ON and two steps in which all the reed switches are turned OFF.
The wet type image forming apparatus according to the first aspect of the present invention may further comprise a developing device to which the ink from the ink tank is supplied, wherein the interval between a first reed switch arranged in an upper end portion of the columnar body and a second reed switch arranged adjacently to the first reed switch is set such that when the ink is supplied to the developing device from the ink tank under a condition in which a liquid surface is present at the upper end portion, an ink amount is decreased by one step.
In this case, the remaining amount judging portion may supply the ink from the ink tank to the developing device when the detecting circuit detects a state showing that all of the n reed switches are in the OFF state immediately after a power turned on, then judges that the liquid surface is present in the bottom tip portion of the ink tank when the ink amount is not decreased by one step, and judges that the liquid surface is present in the upper end portion of the ink tank when the ink amount is decreased by one step.
In order to accomplish the object, an information processing system according to a second aspect of the present invention comprises a wet type image forming apparatus and a processor which processes information and outputs the processed result to the wet type image forming apparatus. In this case, as the wet type image forming apparatus, the wet type image forming apparatus according to the first aspect of the present invention may be employed.